Method for forming centering cavities in billet ends



Nov. 24, 1953 J. w. KELSO 25601545 METHOD FOR FORMING CENTERING CAVI TIES IN BILLET ENDS Filed Sept" 11, 1950 2 sheets-sheet 2 lawentm Ja/m I K5450,

Patented Nov. 24, 1953 METHOD FOR FORMING CENTERING CAVITIES IN BILLET ENDS John W. Kelso, Clairton, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Application September 11, 1950, Serial No. 184,240

1 Claim. 1

This invention relates to a method for forming centering cavities in the ends of seamless tube billets preparatory to piercing.

In the manufacture of seamless tubes by the round billet piercing process, in order to obtain uniform wall thickness it is essential that the piercer point or plug be started through the billet at the exact center of the billet end. In order to accomplish this, it is customary to prepare the lead ends of the round billets by providing a centering cavity therein to accommodate the nose of the piercer plug. Prior to my invention these center cavities were formed by forging, machining or burning.

In order for the centering cavity to function successfully as a guide means, it is essential that the outside end diameter of the cavity be of sufficient size to allow the nose of the piercer plug to be inserted therein without touching the inner wall of the cavity immediately adjacent its front end. If the diameter of the front end of the cavity is not sufiiciently large, as was frequently the case with cavities formed by methods used prior to my invention, the edge formed by the intersection of the inner wall of the cavity and the end face of the billet will fold under during the piercing process and create a lap on the inside surface of the tube. This defect occurs at such a distance away from the end of the tube that it lies beyond the normal crop area and hence makes it necessary to crop 01f substantially more of the finished tube than would ordinarily be done, thereby reducing mill yield and raising production costs.

It has been found that the ideal profile of the centering cavity is in the form of a shallow cone, the depth of which is approximately equal to the radius of the piercer plug nose, and the diameter of the cone base being equal to the original billet diameter minus twice the wall thickness of the pierced shell. Thus if a lap is formed it would be close to the front end of the tube within the normal crop area. A conical centering cavity of this shape and size would be expensive to form by conventional machining or forging processes but is cheaply and quickly made by the method and apparatus I propose.

It is accordingly an object of my invention to provide a method for forming a centering cavity in a billet end comprising the steps of heating the lead end of the billet, directing an intense stream of oxygen under pressure against the center of the heated end to form an initial cavity therein and then flaring the cavity by means of appropriately directed streams of oxygen.

This and other objects will be more apparent after referring to the following specification and attached drawings, in which:

Figure 1 is a side elevational view, partly in section, showing a blowpipe nozzle in relation to a workpiece for performing the operation of my invention;

Figure 2 is a view similar to Figure l but with the nozzle in the second operating stage;

Figure 3 is an end view of the workpiece looking into the cavity formed by the nozzle in the position shown in Figure 2;

Figure 4 is a view similar to Figure 2 but with the nozzle in the third and final operating stage;

Figure 5 is an end view similar to Figure 3 showing the cavity in the workpiece during the third operating stage;

Figure 6 is a side elevational view, partly in section, of the finished workpiece;

Figure 7 is an end view looking into the finished cavity in the workpiece shown in Figure 6;

Figure 8 is a longitudinal sectional View taken on the line VIIIVIII of Figure 9; and

Figure 9 is an end View, partly in section, of the discharge end of the nozzle.

Referring more particularly to the drawings, reference numeral 2 indicates a torch encased in a housing 4 and having a nozzle 6 projecting from the end thereof. Nozzle 6 consists of an elongated body portion 8 having a centrally located fluid passageway it extending therethrough. The front end of nozzle 6 is provided with a large center orifice l2 communicating with the passageway Hi. Four orifices [4 are radially disposed apart around the center orifice 12. The periphery of the body member 8 is undercut as at It adjacent the front end of the nozzle. Four jet openings l8 are spaced around the undercut periphery 90 apart. Jet openings I 8 are so disposed as to be able to emit a jet rearwardly of the front end of the nozzle 6 at an angle slightly less than normal to the longitudinal axis of the nozzle. The purpose for this will be apparent as the description proceeds. As seen in the sectional Figure 8, nozzle 6 is provided with a threaded portion I9 whereby it is screwed into the torch 2. Adjacent to threaded portion is, nozzle 6 is provided with a pair of annular spaces 20 and 22, each of which is provided with an inlet opening 24 and 26, respectively. A supply passageway 28 extends through the torch 2 from inlet 24 to an oxygen supply line 39. Inlet 26 is connected with a mixed gas supply line 32 by means of a passageway 34. Supply line 32 leads to a conventional oxygen and acetylene gas mixer, not shown. The center fluid passageway 10 communicates with a passageway 36 in torch 2 which is connected with an oxygen supply line 38. Passageway I is joined to passageway 35 by means of a conical joint 48. Supply lines 30, 32 and 38 are each provided with a control valve 48, 58 and 52, respectively, for controlling the passage of gas therethrough.

Space 28 is sealed from the other passages by conical joints 40 and 42. Four longitudinal fluid passageways 44 extend from the annular space 28 to the jet openings [8. Four similarly disposed longitudinal fluid passageways 26 extend from annular space 22 to the orifices [4.

The fluid passageways 44 and 49 are so positioned that they are spaced alternately 45 apart. Housing 4 is rotatably supported in bearings 54 and 58 which permit reciprocative as well as rotative movement of the housing 4. Means for reciprocating housing 4 is provided by a motor 58 which is connected to a circular rack 60 through a shaft 62, worm 84 and gears 66 and 58. The housing is rotated by independent means consisting of a motor 19 which is connected to a gear 12 through a shaft It, worm gearing i6 and pinion '18 which, in turn, is carried on bearings 88 and 82. Pinion i8 is elongated to permit forward and backward motion of the torch. Although I have found the above described actuating means suitable for my purpose, it will be noted that any means by which the torch assembly can be reciprocated and rotated in a con trolled manner would be satisfactory.

In operation, the billet section W, which is to be pierced, is placed preferably in a trough 84 having one end adjacent the nozzle 6 of torch 2. Billet W is so positioned that the exact center point of its lead end lies adjacent the front end of nozzle 6. After the billet is properly positioned, valve 58 is turned on to allow the gas mixture to flow from supply line 22 to orifices 14 by way passageway 34, annular space 22 and longitudinal fluid passageways 46. Then the gas mixture is ignited to heat up the front end of billet W. When the proper degree of heat is reached, the preheating gas mixture issuing from orifices i4 is shut off and high pressure oxygen is introduced through supply line 38, passage 3i, fluid passageway 19 and orifice l2. The oxygen issuing from orifice 12 then forms a primary cavity 86. After cavity 86 has been formed the oxygen from orifice I2 is shut off. Oxygen is then introduced through supply line 38, passageway 28, annular space 20, longitudinal passageways 44 and jet openings l8. Simultaneously motor 58 is actuated to move torch 2 forward. The four oxygen streams issuing from openings l8 contact the sides of cavity 86 at the still hot outer edge. Four slots 88 will be cut progressively deeper as the torch advances until the nozzle end contacts the bottom of the primary cavity 85. Now the four slots 88 will extend from the bottom of the primary cavity 86 to point X (Figures 2, 4 and 6) making the same angle with respect to the billet axis as the angle included between the torch centerline and the centerline of jet opening l8 as shown in Figure 8. The torch is then rotated 90 by the actuation of motor 78 causing the four oxygen streams issuing from openings I8 to out out the four conical segments included between slots 88 thus flaring out the cavity. As the torch is rotated, the conical segments between the slots 88 are severed from the billet and fall out leaving the desired conical center cavity 98, as shown in Figures 6 and 7.

The steps in the above-described operation are carefully regulated throughout the entire process so that the finished cavity 98 will be formed in the shape of a shallow cone, the depth of which is approximately equal to the radius of the piercer plug nose which is to be used; and. the diameter of the base thereof is equal to the original billet diameter minus twice the wall thickness of the pierced shell. This shape cavity Will insure the location of a lap is formed well within the normal crop area.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claim.

I claim:

In a method of forming a conical centering cavity in the end of a billet, the steps including applying a heating flame to the area adjacent the center of the end of the billet, forming a substantially cylindrical cavity centrally of the heated end of the billet by directing an oxygen stream thereagainst, and then widening said cylindrical cavity into conical shape by delivering an oxygen stream from substantially the inner end of said cavity directed outwardly and rearwardly at an acute angle to the axis of the billet while at the same time effecting relative rotation about the longitudinal center line of the billet between the billet and said last named stream.

JOHN W. KELSO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,049,807 Bucknam Jan. 7, 1913 1,136,490 Smith Apr. 20, 1915 1,554,407 Coberly Sept. 22, 1925 1,670,495 Coberly May 22, 1928 1,779,612 Coberly Apr. 7, 1931 1,901,803 Davis Mar. 14, 1933 2,017,423 Walker Oct. 15, 1935 2,299,682 Walker July 30, 1940 2,273,809 Kinzel Feb. 17, 1942 2,279,564 Emery et a1. Apr. 14, 1942 2,296,376 Babcock et al Sept. 22, 1942 2,327,496 Burch Aug. 24, 1943 2,537,165 Smith et al. Jan. 9, 1951 

